Why is rendering only showing images from the previous render?
In Render Properties, look at the Post Processing panel. Disable the Sequencer checkbox and Blender will re-render from your 3D scene rather than from the frames in the VSE.

That said, to avoid this kind of thing from happening to myself, I've gotten into the habit of either using a separate .blend file for sequencing or creating a new scene in my .blend file that's specific for sequencing. That way, you can render from your "work" scene and do your VSE work from your sequencing scene. It's a pretty handy workflow.